Berlin 2001 – wissenschaftliches Programm
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MO: Molekülphysik
MO 8: Posters Thursday: Dissociation and other Collision Processes
MO 8.17: Poster
Donnerstag, 5. April 2001, 12:30–15:00, AT3
DISSOCIATIVE EXCITATION MECHANISM IN SLOW COLLISIONS OF Na+ and K+ — •M. Gochitashvili, B. Kikiani, and R. Lomsadze —
In the present work the values for absolute cross sections of electron capture dissociative excitation processes at collisions of Na and K cations with H2 molecules in 0.7-10 keV energy range are given. The measurements were carried out by optical and collision spectroscopy methods. The experimental set up and calibration procedure for the determination of absolute value of cross sections of excitation processes have been described in detail 1 . The comparison of results for dissociative excitation processes of hydrogen molecule by K+ and Na+ - ions shows, that the excitation of the L-line occurs more effectively in the case of K+ - H2 pair. The experimental results are interpreted on a basis of the quasimolecular representation in framework of the quasidiatomic 2 approximation by using the schematic correlation diagrams of molecular orbitals (MO) of colliding particle system. An important point in this connection is that it is necessary to take into account the orientation of molecule axis relative to the direction of the ion beam 2 . This is achieved by using schematic MO correlation diagrams for two different particular the C2V (isosceles triangle) and CooV ( linear conformation) symmetries of the triatomic molecule. Analysis of correlation diagrams shows that for dissociative excitation processes the perpendicular orientation of molecule axis plays a dominant role in formation of excited hydrogen atom H(2p) . In the case of K + - H2 pair excitation of the hydrogen line L after decay of excited molecular states of H2(1s 2p ) or H2 + (2p u) are reached by interaction (rotational interaction) between initial K + - H2 (1s ) 2 and final inelastic channels of K + - H2(1s 2p ) , K(4s) * H2+(2p u) . In the case of Na + -H2 the initial molecular term is promoted to the continuous spectrum and hence for the excitation of H2(1s 2p) molecular state the process of ionization is competitive . This is the reason for the reduction of the excitation cross section of line L in the last case 1. 1. M.Gochitashvili, N.Jaliashvili, R.Kvizhinadze, B.Kikiani, J .Phys. B. 281(1995)2453. 2. O.Yenen,D.H.Jaecks,and P.J. Martin Phys.Rev.A. 35(1987) 1517. 3. Dowek D., Dhuicq D.,Sidis V. And Barat.M. Phys.Rev.A26(1982)746